In an essay published this morning in Scientific American, world wide web founder Tim Berners-Lee is critical of the most successful social networking sites. In the essay, Berners-Lee accuses Facebook of creating a "closed silo of content" that risks fragmenting the web.

Facebook, LinkedIn and other social networking sites represent "one of several threats" to the future of the world wide web, its founder, Sir Tim Berners-Lee has warned.

Some of the web's "most successful inhabitants", such as Facebook and large telecoms companies, have begun to "chip away" at its founding principles, Berners-Lee wrote in a Scientific American journal essay published today.

Social networking sites that do not allow users to extract the information they put into them is a "problem" that could mean the web is "broken into fragmented islands", he said.

Google accused Facebook earlier this month of leaving its 600 million users in a "data dead end" with their contact details and personal information "effectively trapped".

Although Facebook recently began allowing users to download profile information including status updates and photos, the world's most popular social network has been roundly criticised for leaving users' network of contacts "walled" inside its own site.

Berners-Lee warned that such a "closed silo of content" risked leaving the web "fragmented".

"The web evolved into a powerful, ubiquitous tool because it was built on egalitarian principles," he said. "The web as we know it, however, is being threatened in different ways. Some of its most successful inhabitants have begun to chip away at its principles."

He added: "The more you enter, the more you become locked in. Your social networking site becomes a central platform – a closed silo of content, and one that does not give you full control over your information in it."

"The more this kind of architecture gains widespread use, the more the web becomes fragmented, and the less we enjoy a single, universal information space."

We are just shy of the 20 year anniversary of the world wide web. It went live in December of 1990 on Berners-Lee's desktop.